Telephone-exchange system.



C.L.GO0DRUM. TELEPHONE'EXCHANGE SYSTEM.

APPLICATION FILED OCT-11.1916- Patented Dec. 11, 1917.

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C. L GOODRUM. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FI ED-001.11. 191s.

Patented Dec. 11,1917

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Char/e5 L. Good/ am,

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assume.

Application filed october'lL 1916'. Serial No. 3124,9418.

in a connection leads through a plurality of oflices. It may happen that the calling party desires to speak with a second party in the distant oiiice immediately after having concluded his conversation with the first party.

Heretofore, in order to establish a connec tion with the second partys line, the calling party had to reset all the switches involved in the connection. I

In the circuit arrangement of this inven-. tion, if the calling party desiresto establish a connection with such second partys line, he can release the switches in the distant office while retaining the switches in the originating oflice in their set condition and reset a train of switches at the distant oilice to connect with the-line of such second party.

The invention is illustrated in connection with a fast and slow two-wire system. In such systems the connector is provided with one fast relay and two slowrelays. When the connection has been built up as far as the connector, the fast relay thereat is energized in' a circuit controlled at the'substa tion sender. The fast relay controls the first j slow relay. at a front contact, and the second slow relay is controlled at a back contact of the fast relay and a front contact of the first slow'relay. These relays are operated by the sender to transmit impulses to the connector stepping magnets to set theconnector on the wanted line. W hen the called party respends, an electroresponsive switching device such as a side switeh, advances and prepares a release circuit for the switches preceding the connector at the called office. If

the calling party, after setting up the conmen io and concluding the conversation, de-

sires to talk with another party in such office, he actuates a switch at 1115 substation, preferably the sender, which momentarily deenergizes the fast relay. The fast relay in deenergizing closes a circuit for the second slow relay over the front contact of the first slow relay. The second slow relay in Specification of Letters Patent. Patented Deco 15 191 7 energizing causes theclosure of the release I circuit referredto.

Referring to the drawing, Figures 1 and 2 taken together show a circuit arrangement embodying the invention.- The invention will be best understood by describing in detail the operation.

Upon the removal of the receiver at substation A, a line finder (not shown) is automatically set in motionand extends the call ing line to the first selector S, whereupon the stepping relay 100 thereat is energized over the calling line circuit, and in attracting its armature, energizes a slow relay 101. This relay, in attracting its armature, interposes a break in the circuit of release magnet 102 of thefirst selector S. The calling party now operates his sender s to transmit the first digit of the wanted number. This sender may be of the well-known type which interrupts the line circuit anumber offtimes corresponding to the particular digit involved. Upon each retraction of the armature of relay 100 an impulse is transmitted over the following circuit to the primary stepping-magnet 103 of the first selector S,

armature and back contact of relay 100, ar-' mature and front contact of relay 1'01, 0E- normal contact 104:, magnet 103, free pole of battery. The primary magnet 103 thus steps the brushes into operative relation to the desired group of trunks. Upon the first retraction of the armature of relay 100, a slow relay 105 is energized, and, in attracting its armature, energizes the escape magnet 106,

which is constructed to release the side switch from position 1. to DOSltlOn 2, upon itsdeinergization. When the sender 8 restores and maintains the line circuit closed,

the relay 105, after aninterval, retracts its armature, dei nergizing the escape magnet. which thereupon rel ases the side switch into position In p t -2 the f91l9win 011'" cuit is closed for the secondary magnet 1117 to drive the brushes 108, 109' and 110 over the level in which two wire trunks leading to the desired distant oiiice terminate. This circuit is as follows: free pole of battery, magnet 107 and its armature and back contact,

' side-switch arm 114: to ground at the armature and front contact of relay 100, now energized over the line circuit. Idle trunks are those upon Whose test multiples 113 ground is present, and the 'esca e magnet 106 1s arranged to release the si e switch into position '3 upon its energization. 1n position 2 the escape magnet 106 is connected to I attraction of this armature also closes the circuit of a slow relay 151, which interposes a break in the circuit ofrelease magnet 102 of selectors. Since this relay is slow-to release itsarmature, the vibration of the armature of the relay 150, when 0 erated by the sender will not afi'ect the re ease magnet 102. Relay 150 in energizing closes the following circuit for stepping relay 118 of such. selector at the distant office over the trunk conductors 152, 153: free pole of battery at the distant ofiice, right winding of relay 118 thereat, arm 137 and the first con-. tact of the side switch, conductor 152, upper right winding of repeating coil RC, armature and front contact of relay 150, lower right winding of repeating coil RC, conductor 153, arm 138 and first contact of the side switch, left winding of relay 118, to

ground. Relay 118 in energizing closes the circuit of; a slow relay 121 which in attracting its ,armature interposes a break in the circuit of release magnet 123 of the selector S and connects the primary magnet 12% of such selector to the back contact of stepping relav 118. :The selector S is now read-1y to receive the impulses. Upon the operation of the sender by the calling party intransmitting the next digit, the armature of relay 150 vibrates and upon each retraction of the left armature thereof relay 118 transmits an impulse to magnet 124 to step the brushes 126, 127 and 128 into operative relation to the desired group of the trunks'129, 130 and 131, which may terminate in a connector C,

or another selector similar to S. Upon the first retracti n or thearmature of r lay 118,

a slow relay 132 is energized, and in attracting its armature energizes the escape magnet 133 of selector S, which magnet is constructed to release the side switch from position 1 to position 2 upon its deenergization.

When the sender s restores, it maintains the line circuit closed. The maintained energ1- zation of relay 118 causes the slow relay 132 ing circuit: free pole of battery, magnet 134,

its armature and back contact, arm 135 and its second contact, armature and front contact of relay 118 to ground. As in the case of selector S, idle trunks are those upon whose test multiples 131 ground is present. Consequently, when the test'brush 128 encounters a grounded test multiple 131, the

escape magnet 133 becomes energized over a circuit including the arm 136 and its second contact and test brush 128. The escape magnet is constructed to release the side switchfrom position 2 to position3, upon its energization. In moving out of position 2, the side-switch arm 135 opens the circuit of the secondary stepping magnet 134:, thus stopping the selector with the brushes 126, 127 128 upon the terminals of the seized trunk.

In position 3 side-switch arms 137, 138 GX tend the callin line to the connector 0, Fig.

2, cutting off t e bridge at the second selector containing the stepping relay 118. In moving intoposition 3, arm 120 extends the circuit of release magnet 123 to release conductor 139 extending to the connector. The ground upon this conductor at the armature and back contact of stepping relay 7 is removed before the release magnet 123 can energize.

Relay 7 is energized over the conductors 152, 153, and at its armature and front contact, energizes a slow relay 8. This relay, in attracting its right armature, interposes a break in the circuit of the test conductor 9 leading back to the preceding switch, and in attracting its left armature interposes a break in the circuit of the release magnet its right armature, an impulse is transmitted to the primary magnet 10 of the connector over the following circuit: armature and back contact of relay 7, right armature and front contact of relay 8, whichis slowescape magnet 13 of the connector side switch: free pole of battery, magnet 13,-

arm 4 and its'first contact, right armature and front contact of relay 12, conductor 14, armature and back contact of ringing cutoff relay RCO to ground. The escape mag net is constructed to release the side switch from position to position upon its deenergization in the well-known manner.

the sender 8 restoresand maintains the stepping relay 7 energized, relay 12 after an the secondary magnet 15 for the primary 13 which releases the side switch into posi-.

magnet 10 in the stepping circuit.

The calling party now operates his sender s to transmit the units digit of the wanted number. Upon each retraction of the armature of relay 7, an impulse is'transmitted to the secondary magnet 15 over the 'circuit previously traced to arm 3, whence it passes to the magnet 15, free pole of battery. Magnet 15 steps the positioned brushes 16, 17 and 18 over the selected groupof terminals containin those of the Wanted line'19, 20, and 21. pon the first retraction of the armature of relay 7 the slow relay 12 energizes as before, and again closes the circuit of escape magnet 13. When the sender restores and maintains the relay 7 energized, relay 12, after an interval, becomes deenergized opening the circuit of escape magnet Whenopens the circuit of escape magnet 13, which, in denergizing, releases the side switch into position 4. In position 1, talking current is supplied to the called llne over the following circuit: free pole of battery, leftwinding of relay 28, conductors 29, 30,. arm 1, brush 16, multiple 19, through the telephonic apparatus at substation B, multiple 20, brush 17, arm 2 and its fourth contact, conductors 31 32', right winding of relay 28, to ground. ltelay 28 in attracting its right armature interposesa break in the circuit of release magnet RM. The. subscribers may now converse. I Upon the conclusion of the conversatio the parties replace their receivers, which results in the closure of the circult of release magnet RM as follows: free pole of battery, right Winding of magnet RM, conductor 33, armature and back contact of relay 28, off-normal contact PON, conductor 36, left armature and back contact of relay 8, conductors 37 38, left armature and back contact of relay 28, inner-right armature of relay 8, to ground at the armature and back contact of relay 7. When the connector brush shaft reaches its normal position the contact PON opens and the release magnet is deenergized. The deenergization of relay 28 applies 4 ground to release conductor 9, over the right armature and back contacts of relays 7 and tion Arm 6, in moving into position 3,

grounds the test multiples 21 of the selected line to cause the saineto test busy to other connectors, and operates. the cut-off relay of such line In this position magnet 13 is again energized over the following circuit: free pole of battery, magnet 13, arm 5 and its third contact, conductor 14, armature and back contact of relay RCO to ground. Magnet 13 at its armature and front contact connects the source of signaling current 22 to the called line over the followingcircuit: free pole of generator 23 or, battery 24:, de pendent upon the position of the signaling apparatus 22, commutator 'brush- 25,'re'lay RCO, armature and front "contact of ma net 13, arm 2 and its third contact, brush"1%, multiple 20, bell 25, condenser 26, multiple 19, brush 16, arm 1 and its third contact,

conductor 27, armature and front contact of relay 7 to ground.-' When the called party re-' moves his receiver, relay 'RCO energizes and 8, andthe left armature and back contact of relay 28, assuming that the called party has replaced his receiver, If, however, the called party has not replaced his receiver, an impulse is transmitted to the release magnet 123 over the following circuit: armature and back contact ofrelay 7, right armature and front contact of slow relay 8, which maintains its armatures attracted for an interval after it's circuit is broken by. the retraction of the armature of relay 7, 'conductors 11, 39, left armature and front contact of relay 28, conductor 38 to conductor 9. This ground applied to conductor 9,

-energizes release magnet 123 of the selector S. The replacement of the receiver by the calling party deenergizes repeating relay 150 which opens the circuit of slow relay 151. which at its armature and back contact closes the circuit of the release magnet 102 lectors. I i v Assume that the calling party upon the conclusion of the conversation desires to talk witha subscriber in the same office in which theline. of the party withwhom he has of selector S and of any-other similar sc just been speaking terminates. In this'event I the calling party doesnot replace his receiver but operates the sender}; to transmit any digit, for example, 1 .v This interrupts the circuit of repeatlng relay 150, which, in retract ng its right armature, deenergizes relay 7 at the connector. Relay 7 in retract-- ing its armature energizes the slow relay 12 over the following circuit: free pole of battery, relay 12, right armature and front contact of relay 8, armature and back contact of relay 7 to ground. Belay 12 in attracting its right armature closes the following circuit for the relay 60: armature and back contact of relay RCO, right armature and S and also restores the associated side switch. The restoration of'selector S deenergizes relay 7 whiclrcauses the energizatlon of the release magnet RM of the connector over the followii'ig'circuitz free pole of battery, right winding of magnet RM, right armature and back contact of relay 28, off-normal contact PON, conductors 36, 44, left armature and back contact of relay 8, conductors 37, 38, left armature and back contact of relay 28, inner right armature and backcontact ofrelay 8, armature and back contact of relay 7 to ground. When the connector brush shaft reaches'its normal position, contact PON is opened and the release magnet is deenergized. The connector release magnet in restoring restores the side switch.

During the operations just described the slow relay 151 has been maintained continuously energized, and consequently the selector at the originating o'lfice has not been. released. The calling subscriber now transmits the necessary number of sets of impulses to set a train of switches to connect with another called line. These operations are the same as the above operations and. 'will not, therefore, bedescribed again.

In case the calling party in setting up the first connection receives the busy signal, due to the engaged condition of the wanted line, he may restore the switches at the distant office without restoring those at the oflice to which he belongs, and reset a train of switches at the distant oiiice on the line of another party. The operations in this event are as follows: Upon the restoration of the sender s after having transmitted the im-' pulses corresponding to the units digit, relay 7 rema nsienergized, and after an interval, slow relay 12 becomes deenergized. The retraction of the left armature of this relay closes the circuit of release magnet RM of the connector as follows, the multiple 21 being grounded, since the substation B is not being made slow for this purpose.

nsane conductor 42, arm 6 and its second contact,

brnsh 18, to grounded test multiple 21. This circuit is closed before the left armature of relay 12 is retracted long enough to deenergize the escape magnet 13, this mag lease magnet BM in attracting its left armature locks itself to ground at the outer right armature of relay 8, and in attracting its inner rightarmature applies busy tone from abusy-tone apparatus to talking conductor 31, and thence to the calling line. The calling party desiring to set up a .connection with another subscriber in the distant office now operates his sender without replacing the receiver. Relay 12 in attracting its right armature in response to the operation of the sender closes the following circuit for the relay 60' free pole of battery, left windingof relay 60, outer armature and front contact of magnet RM, arm 4 and first Contact, right armature and front contact.

of relay 12 to ground at'the armature and back contact of relay RCO. Relay 60 in attracting its armature grounds release conductor 9, from which the release magnets of the selectors at the oiiice in which the called line terminates are branched 011'. These switches release as described.

busy: free pole of battery, right winding of.

The calling party then, by means of the sender, operates the repeating relay 150 and builds up a connection to the line of another subscriber as described.

In case the called party fails to respond to the-ringing of the bell25, the calling party by operating his sender momentarily deenergizes relay 7 as described, which transmits an impulse to slow relay 12. Re-

, lay 12 in attracting its right armature transmits an impulse over the following circuit to relay 60: free pole of battery, right winding of relay 60, conductor 34, arm 4 in its third contact, right armature and front contact of relay 12 to ground at the armature and back contact of relay RCO. Relay 60 in attracting its armature grounds the release conductor 9 from which the selector release magnets are branched oif, whereupon these selectors are restored. The restoration of selector S results in the restoration of the connector. The calling party may now build up a connection with another line as described.

If the calling party fails to replace his receiver, the'called party can secure the attention of an attendant at the exchange by actuating his receiver hook, which causes the intermittent illumination of a lamp 40 over the following circuit: free pole of battery, right winding of magnet RM, conductor 33, right armature and back contact of laconic relay 2:8, arm l1, lamp 46 to ground. The release magnet does not operate when this circuit is closed, due to the resistance of lamp What is claimed is:

1. In a telephone exchange system, the combination with telephone lines, oilices wherein said lines terminate, linlrcircuits in terconnecting said oliices including auto matic switches, means for setting said switches to interconnect a line in one oflice with a line in a distant oilice, and means controlled by the calling party for restoring all the switches or for restoring the switches at the distant office only, and for setting s *itches therein to connect with another line. I

2. In a telephone exchange system, the combination with telephone lines, offices wherein said lines terminate, two-wire link circuits interconnecting said ofiices includin automatic switches, means for setting said switches to interconnect a linein'onc office with a line in a distant oiiice, and means controlled by the calling party for restoring all the switches or for restoring the switches at the distant ofice only, and

for setting switches therein to connect with another line.

3. In a telephone exchange system, the combination with telephone lines, oilices wherein said lines terminate, link circuits interconnecting said oflices including automatic selector and connector switches, a sender at the calling substation for setting said switches to extend the calling line to a combination with telephone lines terminating in difi'erent offices, trunk circuits interconnecting said oilices and including selectors and connector, a sender for controlling said switches, a set of repeating relays comprisin a fast and aslow relay in said trunk leading to the called omce and operated by said sender to set the switches thereat, a release circuit for the switches in the calling oiiice controlled at a hack contact of said slow relay, a fast slapping relay at said connector, a circuit therefor controlled at a front contact of said fast repeating relay,

'a first and second, slow relay at said connector controlled respectively at front and back contacts of said stepping relay, a re- I lease circuit for the switches at the called oilicc controlled at a hack contact of said first operated to close said second release circuit slow relay, a second release circuit for the switches at the called oflice controlled at, a front contact of said second slow relay, means for preparing said circuit actuated when the connector is set on the called line, said sender when actuated after the connector is established momentarily deinergizing said fast repeating relay to render said fast relay at the connector momentarily inert whereupon'tlie second slow relay is to restore the switches at the called oilice, and a manual switch associated with Said sender for permanently opening the line circuit, whereupon the maintained delinergization of. the fast repeating relay ind fast stepping relay causes the decnergization of their associated slow relays which in deenergizing close the release circuits at both ofiices.

5. In a telephone exchange system, the combination with telephone lines, connectinc circuits including automatic switches a apted to interconnect said lines and restoring means for each of said switches, of means under the control of the calling party for actuating the restoring means of all of said switches, or for actuating the restoringmeans of the switch connected to the called line and of a number of'preceding switches only, and for setting up a connection to an= other called line overthc set switches and other switches.

6. In a telephone exchange system, the combination with calling and called telephone lines, a connector wherein said lines terminate, trunk circuits including selectors, a sender for controlling said selectors to effect connection to said connector over said trunk circuits, and to set the same on a called line, a manual switch, restoring magnets for said switches, means associated with said connector adapted to be operated in one manner by said manual switch to cause the actuation of all of said restoring magnets,

and to be operated by said sender in another manner after the connection has been established to actuate the connector restoring magnet and certain only of the selector "re storin magnets.

7. n a telephone system,- the combination with telephone lines, connecting circuits in-- eluding automatic numerical switches for interconnecting said lines, means controlled 120 at the'calling station for restoring a part only of the selectors involved in a-connection and forcontrolling other selectors over the unrestored switches to build up another connection.

8. Inatelephone system, the combination with telephone lines, automatic switching means for interconnecting said lines, meanscontrolled at the calling station for restoring a part only'of the automatic switching means involved in. a connection and for employing the remaining part in building up another connection.

9., In a telephone system, the combination with telephone lines, automatic switching 5 means for interconnecting said lines, means ployin the remaining part in building up another connection, and for restoring all of it the automatic switching means involved in the connection.

In Witness whereof, I hereunto subscribe my name this 9th day of October, A. D. 1916.

CHARLES L. GOGDRUM. 

